cmd/guru: skip broken test for old Go versions for now

Updates golang/go#24421

Change-Id: Iedcb629135802f78e8f149b377f34e49c8019fe9
Reviewed-on: https://go-review.googlesource.com/106435
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

cmd/guru/guru_test.go

@@ -259,6 +259,11 @@ func TestGuru(t *testing.T) {
 			// tests once we drop support for go1.8.
 			continue
 		}
+		if filename == "testdata/src/referrers/main.go" && !contains(build.Default.ReleaseTags, "go1.11") {
+			// Disabling broken test on Go 1.9 and Go 1.10. https://golang.org/issue/24421
+			// TODO(gri,adonovan): fix this test.
+			continue
+		}
 
 		json := strings.Contains(filename, "-json/")
 		queries := parseQueries(t, filename)